Over an emphatic dissent by its foremost conservatives, a federal appeals court on Tuesday reaffirmed its groundbreaking ruling requiring a state to show strong justifications for laws that discriminate based on sexual orientation, a precedent likely to scuttle bans on same-sex marriage in several Western states.

The Ninth U.S. Circuit Court of Appeals preserved, as a binding precedent, its decision in January that antigay laws are subject to "heightened scrutiny" and can be upheld only if they serve some important public purpose. The ruling by a three-member panel led by Judge Stephen Reinhardt said lawyers violate that standard if they dismiss prospective jurors because they are gay or lesbian.

The court relied on its interpretation of a June 2013 U.S. Supreme Court decision that granted same-sex married couples equal rights to federal benefits. Although that ruling did not declare a new legal standard, Reinhardt said it showed that the high court "refuses to tolerate the imposition of a second-class status on gays and lesbians."

On Tuesday, the appeals court said a request by an unidentified judge for a new hearing before a larger panel had failed to win majority support on the full court.

Since the appellate court's ruling, the governors of Nevada and Oregon, both part of the nine-state circuit, have refused to defend their states' laws against same-sex marriage, saying they could not survive the appeals court's new standard. A similar prediction, in harsher language, came Tuesday from judges who disagreed with the decision.

The ruling "in the view of many ... precludes the survival under the federal Constitution of long-standing laws treating marriage as the conjugal union between a man and a woman," said Judge Diarmuid O'Scannlain. His dissent from the refusal to grant a new hearing was joined by fellow conservatives Carlos Bea and Jay Bybee.

O'Scannlain said the Ninth Circuit panel "invented" a new legal standard, misinterpreted the Supreme Court ruling, and engaged in "an exercise of raw judicial will" that other courts should disregard.

Nevada's marriage law, upheld by a federal judge, is awaiting review by the Ninth Circuit. Another federal judge has overturned Idaho's ban on same-sex marriage, citing last year's Supreme Court ruling. Idaho's governor, C.L. "Butch" Otter, has asked the Ninth Circuit to bypass the normal three-judge panel review and send the case directly to an 11-member panel, which could reconsider the court's discrimination standard.